The invention relates to the testing of semiconductor devices, and more specifically to a method of transporting and positioning of Ball Grid Array (BGA) semiconductor devices during device transportation and testing.
The present invention relates to a universal production Ball Grid Array (BGA) socket for establishing solder less contact between the conductive balls of a ball grid array package and the sockets for transporting or testing of BGA semiconductor devices.
There presently exist several methods for packaging semiconductor devices. One popular type of semiconductor packaging is referred to as Quad Flat Pack (QFP), which is a type of peripheral lead package. Another type of packaging technology is referred to as Ball Grid Array (BGA) packaging where conductive ball leads are placed over the entire surface of a chip instead of only around the edges of the chip.
A BGA package includes a plastic or ceramic carrier containing a semiconductor circuit chip and having a plurality of spaced apart contact balls arranged over the bottom face of the carrier or substrate. This plurality of balls is adopted to make electrical connections with a printed circuit board or with other BGA chip or semiconductor component mounting surfaces. This allows for more leads to be placed in a given package size and for tolerances which are looser than peripheral lead type tolerances.
One manufacturing process which can lead to ball deformation is that of testing and particularly testing at high temperatures. After a semiconductor device has been fabricated it undergoes a variety of tests to ensure its functionality and reliability before it is shipped to the customer. If testing is performed at elevated temperatures, contact ball deformation becomes more likely.
Once the testing has been completed and the device returns to ambient temperatures, indentations in the balls due to the pressure exerted thereon may remain.
From the foregoing it is clear that BGA techniques require that the contacting balls are placed adhering to reasonable tolerances, that the pressure exerted while making contact is not excessive and that making the contacts is relatively easy, that is the BGA semiconductor device carrier has some freedom of motion in the plane of contact.
FIGS. 2a and 2b show the Prior Art device input arm kit, both in side view and a cross sectional view. Spring 21 exerts downward pressure on pick-up shaft 10 for better contact with the target socket. The head 24 of the pick up shaft 10 does not have chamfered sides and does therefore not assist in orienting the device kit properly with respect to. the target socket. There is also no provision which allows motion of the pick-up shaft 10 with respect to the target socket independent of the top plate or body 22 of the input arm assembly. This means that for any movement or orientation of the input arm assembly with respect to the target socket the entire assembly repositions itself including the pick up shaft 10. The BGA device (not shown) is attached for transportation to the head 24 of the pick up shaft 10 by means of vacuum suction, the vacuum is provided through a channel which runs through the center of the pitch up shaft 10 (not shown).
Stabilizing pin 23 is used for dampening any motion which might occur between the pick up shaft 10 and the body of the kit 22. Clips 16 are provided for manual handling of the input arm kit. The input arm is used for all movement of BGA devices (such as to the hot plate and the input shuttle) except for the testing and output positions. The test arm assembly is different from the input arm assembly, the Prior Art test arm assembly is described in detail under FIGS. 9a and 9b following.
FIGS. 9a and 9b show the Prior Art BGA device test arm kit together with a cross section of this kit. This assembly is similar to the previously described Prior Art device kit, FIGS. 2a and 2b. The main difference between the Prior Art input arm assembly (FIGS. 2a and 2b) and the test arm assembly (FIGS. 9a and 9b) is that the test arm assembly has a top plate 93 and a self guided rest piece where the body of the input arm assembly (FIGS. 2a and 2b) consists of one plate. The pick up shaft 90, FIGS. 9b, protrudes through the top plate 93. A stabilizer pin 92 is provided to dampen any motion which might occur between the pick up shaft 90 and plate 93 of the test assembly arm. A spring 97 of proper tension is provided to press or urge the head 98 of the pick up shaft 90 into the socket of the target plate or shuttle. Clips 16 are provided for manual handling of the test arm kit.
U.S. Pat. No. 5,766,021 (Pickles et al.) shows a reusable socket for making electrical connection between a BGA type package and a test fixture.
U.S. Pat. No. 5,730,606 (Sinclair) shows a universal production BGA socket for mounting the BGA on a circuit board.
U.S. Pat. No. 5,731,709 (Pastore et al.) shows a device for testing BGA.
U.S. Pat. No. 5,746,608 (Taylor) shows a surface mount socket for an electronic package.
It is the objective of the present invention to provide for highly accurate and dependable movement of semiconductor devices within the semiconductor device manufacturing and testing environments.
It is a further objective of the present invention to increase the product handling capability within the semiconductor manufacturing and testing environments by increasing the number, type and size of semiconductor devices that can be transported.
As shown in cross section in FIG. 5, a semiconductor device 52 having a semiconductor device mounting support 54 with a periphery 51, a plurality of conductive vias 53xe2x80x2 formed in the semiconductor device mounting support 54, a semiconductor die 52 mounted on the semiconductor device mounting support 54 and electrically coupled to the plurality of conductive vias, a plurality of conductive balls 53 attached to the semiconductor device mounting support 54 and electrically coupled to the semiconductor die 52 through the plurality of conductive vias 53xe2x80x2. FIG. 7 shows an input pocket 72 for receiving the semiconductor device and having a plurality of semi-circular holes 71 so that the semiconductor device 52 can be placed into the input pocket 72 such that the plurality of semi-circular holes 71 of the input pocket is providing proper positioning to the plurality of conductive balls 53 that is attached to the semiconductor device mounting support.
It is a further objective of the present invention to allow implementation of the present invention without having any impact on semiconductor manufacturing or testing apparatus other than the positioning kit which is the subject of the present invention.
According to the present invention, a plate is added to the kit which is used to position the BGA semiconductor device. The BGA kit guides or positions the BGA device into position for testing and other required processing operations such as device burn-in. The kit guides the BGA device into a device pocket in the target plate. The plate which has been added to the BGA device kit is placed on ball bearings to allow ease of movement in a direction which is lateral or perpendicular to the direction of the movement of insertion of the input arm or the test arm into the target socket. Misalignment between the input arm (when inserting a BGA device kit into a BGA device target pocket for testing, burn-in, etc.) or a BGA test arm (during testing of a BGA semiconductor device) and the target socket can in this manner be compensated for.
A BGA device handling apparatus is used for positioning BGA semiconductor devices within the following fixtures:
hot plates where the temperature of the BGA device can be controlled over an extended period of time for such purposes as device burn-in, reliability testing, aging, etc.; BGA semiconductor devices are placed or loaded into the hot plates by means of an input arm.
input shuttle which allows for a multiplicity of BGA devices to be entered into a particular station for further operations of testing or manufacturing; BGA semiconductor devices are placed or loaded into the input shuttle by means of an input arm.
output shuttle which removes a multiplicity of BGA devices from a testing or manufacturing station; BGA semiconductor devices are placed or loaded into the output shuttle by means of an output arm which is of the same design as the output arm.
docking plate which allows a multiplicity of BGA devices to be retained for an extended period of time due to a interruption in their testing or manufacturing sequence; BGA semiconductor devices are placed or loaded into the docking plate by means of an test arm which provides proper guidance of the socket to the handler.
testing plate, BGA semiconductor devices are placed or loaded into the testing station by means of the test arm.
The above described shuttles and plates into which the BGA device is inserted or positioned are for the purpose of the present invention referred to as target plates. The sockets within the target plates into which the BGA device is inserted is for the purpose of the present invention referred to as target sockets.
From the above enumeration it is clear that for BGA device testing and manufacturing operations different BGA semiconductor device handling assemblies are used, that is the input test arm, the socket and the docking plate. The input arm positions the input kit with respect to the target plate, the test arm positions the BGA device kit with respect to the test plate. These two or more assemblies, that is the input kit and the test kit, are addressed as embodiments within the scope of the present invention.
In addition, the prior art single guide pin is being replaced by two guide pins mounted on the plate and placed on ball bearings which results in more accurate and dependable positioning of the BGA device kit.
Also, according to the present invention, increased flexibility in transporting and handling of BGA chip carriers is accomplished by modifying the head of the pick-up shaft of the BGA device kit which moves the BGA device between different positions. The input arm moves the BGA device kit to and from the hot plate and the input shuttle. The input arm can further be used for any other required movement of the device. The test arm moves the BGA device kit to the test socket of the BGA test plate. This increased flexibility in transporting or positioning a device under the present invention is required to assure that a plurality of device sizes and types does not have a negative effect on manufacturing throughput and consequently on overall BGA device cost.
Modification of the Prior Art and presently used BGA device positioning kits in accordance with the present invention does not impose any requirements on other existing equipment in the BGA device manufacturing and testing environment.